The pre-B cell receptor (pre-BCR) expressed during the early stages of B lymphocyte development is a heterodimer of immunoglobulin heavy chain (IgH) with surrogate light chain, which is an Ig-light-chain-like molecule composed of the non-covalently linked Lambda 5 (λ5) and VpreB proteins. The pre-BCR is believed to control IgH repertoire selection and proliferation of differentiating B lymphocytes. The SL156 antibody reacts with a conformational epitope of the pre-BCR in transfected X63-Ag8.653 cells but not with surrogate light chain, λ5, or VpreB in the absence of IgH. It detects pre-BCR on pre-B cell lines, but not on pro-B cell lines or IgM-positive splenocytes. It also detects pre-BCR on the surface of pre-B cells, but not on Ig light chain (IgL)-positive B lymphocytes, from the bone marrow of normal mice. It has been noted that the cell-surface expression of pre-BCR is upregulated after a one-hour incubation of bone-marrow leukocytes in tissue culture medium at 37°C. After immunization, cell-surface pre-BCR is detected on a subset of splenic IgL+ germinal-center B lymphocytes.
The antibody was conjugated to BD Horizon BUV615 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome with an Ex Max near 350 nm and an Em Max near 615 nm. BD Horizon Brilliant BUV615 can be excited by the ultraviolet laser (355 nm) and detected with a 610/20 filter and a 595 nm LP. Due to the excitation of the acceptor dye by the blue/yellow-green laser line, there may be significant spillover into channels detecting PE-CF594 like emissions (eg, 610/20-nm filter).